Effect of nacre extract from pearl oyster shells against behavioral and psychological symptoms of dementia in senescence-accelerated mouse P8 (SAMP8)

Abstract

Pearls have been used in traditional Chinese medicine for the treatment of myopia, epilepsy, and palpitations. We previously demonstrated that the intraperitoneal administration of nacre extract from pearl oyster shells prevents lipopolysaccharide-induced anxiety and depression-like behavior. In this study, nacre extract was orally administered to senescence-accelerated mice-prone 8 (SAMP8) mice at 125 ppm and 250 ppm for 26 weeks. Behavioral tests were performed at 28 weeks of age, followed by molecular analysis at 31 weeks. Administration of nacre extract suppressed anxiety and depressive behavior in SAMP8 mice. In addition, nacre extract ameliorated aggressive behavior and disruption of circadian rhythms in SAMP8 mice. Histological analysis showed that nacre extract prevented neurodegeneration in the hippocampus. RNA sequencing analysis of the brain revealed that nacre extract suppressed endoplasmic reticulum (ER) stress. In addition, nacre extract also suppressed increase in expression of inflammation-related proteins, such as tumor necrosis factor-alpha and interleukin-1. These results suggest that the oral administration of nacre extract suppresses behavioral alterations by suppressing ER stress and inflammation associated with aging in SAMP8 mice.

Keywords

• Senescence-accelerated mice P8
• Nacre extract
• Behavioral and psychological symptoms of dementia
• Endoplasmic reticulum stress
• Inflammation